Patent GB-437049-A (GB)
Title: A process for dyeing animal fibres
IPC: D06P1/12
Filed: 1934-05-18
Abstract: Azo dyes, forming on the material.--Animal fibres such as wool or silk, with or without an admixture of other material such as cotton or artificial silk, which have been dyed by causing a diazotized amine to couple with the fibres, are treated to change the colour of the dyeings by subjecting the dyed fibres to the action of warm or hot aqueous solutions of one or more metallic compounds or salts of chromium, copper, nickel or cobalt and thereafter rinsing and drying. The following examples are specified: (1) A yellow dyeing, produced on natural silk yarn by treatment in a 1 per cent soda ash solution at 50 DEG  C. containing a wettingout agent, draining off surplus liquor, treatment for 45 minutes in a cold solution of diazotized 2 - methoxy - 5 - nitraniline neutralized with sodium bicarbonate and rinsing, is changed to a terracotta brown by placing in an aqueous solution at 30--40 DEG  C. of copper sulphate and acetic acid, heating slowly to about 95 DEG  C., maintaining at 90--95 DEG  C. for \ba1/2\be--\ba3/4\be hour, rinsing and drying.  (2) An orange brown dyeing, produced on wool yarn by treatment with diazotized b -naphthylamine, is changed to a dark brown of improved fastness by placing in an aqueous solution at 50--60 DEG  C. of sodium bichromate and sulphuric acid, heating slowly to boiling, so maintaining for \ba3/4\be--1 hour, rinsing and drying.  (3) A dull yellow or gold dyeing, produced on natural silk yarn by treatment with diazotized a -naphthylamine, is changed to a dark brown of improved fastness by placing in an aqueous solution at 30--40 DEG  C. of potassium bichromate and sulphuric acid, heating slowly to 95--100 DEG  C., maintaining at 95 DEG  C. for \ba3/4\be--1 hour, rinsing and drying. (4) An orange brown dyeing, produced on wool yarn by treatment with diazotized 2 - methoxy - 4 - nitraniline, is changed to a brownish maroon of good fastness to light by placing in an aqueous solution at 50 DEG  C. of copper sulphate and acetic acid, heating slowly to 95 DEG  C., maintaining at or near the boil for \ba3/4\be--1 hour, rinsing and drying.  (5) An orange brown dyeing, produced on wool yarn by treatment with diazotized a -aminoanthraquinone, is changed to a dark brown of improved fastness by placing in an aqueous solution at 50 DEG  C. of copper sulphate and acetic acid, heating slowly to 95 DEG  C., maintaining at or near the boil for \ba3/4\be--1 hour, rinsing and drying.  (6) A reddish orange brown dyeing, produced on woollen cloth containing cotton and viscose artificial silk by treatment with a mixture of diazotized a -naphthylamine and diazotized 4-nitro-2-aminotoluene, is changed to a dark brown with contrasting effect threads by placing in an aqueous solution at 30--40 DEG  C. of sodium bichromate and sulphuric acid, heating slowly to boiling, so maintaining for \ba3/4\be--1 hour, rinsing and drying.  (7) An orange brown dyeing, produced on woollen cloth by treatment with diazotized 2 - methozy - 4 - nitraniline, is changed to a brownish maroon by placing in a aqueous solution at 30 DEG  C. of copper sulphate, heating slowly to 95 DEG  C., maintaining at or near the boil for \ba3/4\be--1 hour, rinsing and drying.  (8) An orange brown dyeing, produced on loose wool by treatment with diazotized b -naphthylamine, is changed to a dark brown of improved fastness by placing in an aqueous solution at 50--60 DEG  C. of sodium bichromate and sulphuric acid, heating slowly to the boil, so maintaining for \ba1/2\be--1 hour, rinsing and drying.  Other specified diazo compounds are those of 3-chloro-1 - aminonaphthalene, 4 - nitro - 1 - aminonaphthalene, 1 : 5 - diaminonaphthalene, Brönner acid, 4-nitraniline, benzidine, tolidine, o - aminoazotoluene, dianisidine, 4 - aminoacenaphthene, 4 : 8-diamino-1 : 5-dihydroxyanthraquinone, 2 - methoxy - 4 - chloraniline, 3 - nitro - 4 - aminophenetol, o - nitrobenzidine and 1 : 5-diaminoanthraquinone.